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Adopted from the parallel tracing branch: - Add "path" argument to checkDeferredNode, checkVariableDeclaration, and checkExpression trace points, matching the TypeScript reference implementation which includes the source file path for these events. - Add PopAll() method to both Tracing and CheckerTracing types, matching TypeScript's tracing.popAll() which closes all open events at once. This is used in the language server session for cleanup.
Match TypeScript's behavior of using `aliasSymbol ?? symbol` when determining firstDeclaration for type descriptors. Previously only the type's direct symbol was used, causing union types created via type aliases (e.g. `type Nullable<T> = T | null | undefined`) to be missing their firstDeclaration. Now these types correctly point back to their alias declaration site. On the typeslayer project this adds ~2,800 firstDeclaration entries per checker for union types that have an aliasSymbol.
Include TypeFlagsTemplateLiteral in the Display() condition alongside
TypeFlagsLiteral, so that template literal types (e.g. `${number}`)
get their string representation in the trace output. This goes beyond
TypeScript's current behavior but provides useful diagnostic info for
these types that would otherwise have no display or firstDeclaration.
Extend Display() to compute typeToString for Union and Intersection types in addition to Anonymous, Literal, and TemplateLiteral types. Anonymous unions and intersections can't have firstDeclaration (they have no symbol or aliasSymbol), but display text makes them identifiable in trace output. For example, a previously opaque union now shows: display: "CodeRouteToPath<TRouter> | FileRouteToPath<...>" This increases display coverage from ~39% to ~75% of all types.
jakebailey
reviewed
Feb 27, 2026
| return NewCheckerWithTracer(program, nil, nil) | ||
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| func NewCheckerWithTracer(program Program, tracer TypeTracer, tr *tracing.CheckerTracing) (*Checker, *sync.Mutex) { |
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I don't particularly like that we have this variant... what was wrong with the approach I had in my branch?
jakebailey
reviewed
Feb 27, 2026
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| func (c *Checker) checkDeferredNode(node *ast.Node) { | ||
| c.tracing.Push(tracing.PhaseCheck, "checkDeferredNode", false, "kind", strconv.Itoa(int(node.Kind)), "pos", strconv.Itoa(node.Pos()), "end", strconv.Itoa(node.End()), "path", ast.GetSourceFileOfNode(node).FileName()) |
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All tracing calls should do an if c.tracing != nil check; these are expensive operations to be doing on ever single node.
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this is a work in progress PR to add tracing so we can get types.json and trace.json files as was in the TypeScript codebase.